// Native
const { homedir } = require('os');
const path = require('path');

// Packages
const fs = require('fs-promise');
const ms = require('ms');

// Ours
const { get: getUser } = require('./user');

// `8h` is arbitrarily used based on the average sleep time
const TTL = ms('8h');

let file = process.env.NOW_JSON
  ? path.resolve(process.env.NOW_JSON)
  : path.resolve(homedir(), '.now.json');

function setConfigFile(nowjson) {
  file = path.resolve(nowjson);
}

function save(data) {
  fs.writeFileSync(file, JSON.stringify(data, null, 2));
}

/**
 * Reads the config file
 *
 * Optionally, always queries the API to get the user info even if the
 * config file is not present
 *
 * @param  {Boolean} force [false] Queries the API even if the config
 *                                 file is not present. If `true`, `token`
 *                                 *must* be specified
 * @param  {String} token          Will be used to autenticate in the API
 *                                 if `force` is `true`
 * @param  {String} apiUrl         URL of the API to be used
 * @return {Object}
 */
async function read({ force = false, token, apiUrl } = {}) {
  let existing = null;
  try {
    existing = fs.readFileSync(file, 'utf8');
    existing = JSON.parse(existing);
  } catch (err) {}

  if (!existing && force && token) {
    const user = await getUser({ token, apiUrl });
    if (user) {
      return {
        token,
        user: {
          uid: user.uid,
          username: user.username,
          email: user.email
        }
      };
    }
    return {};
  }

  if (!existing) {
    return {};
  }

  if (!existing.lastUpdate || Date.now() - existing.lastUpdate > TTL) {
    // TODO: update `teams` info
    const token = existing.token;
    const user = await getUser({ token });

    if (user) {
      existing.user = user;
      existing.lastUpdate = Date.now();
      save(existing);
    }
  }
  return existing;
}

/**
 * Merges the `data` object onto the
 * JSON config stored in `.now.json`.
 *
 * (atomic)
 * @param {Object} data
 */
async function merge(data) {
  const cfg = Object.assign({}, await read(), data);
  save(cfg);
}

// Removes a key from the config and store the result
async function remove(key) {
  const cfg = await read();
  delete cfg[key];
  fs.writeFileSync(file, JSON.stringify(cfg, null, 2));
}

module.exports = {
  setConfigFile,
  read,
  merge,
  remove
};